• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1932-1936
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• 2008

A new analytical method using 1-(2-pyridylazo)-2-naphthol modified $SiO_2$ nanoparticles as solid-phase extractant has been developed for the preconcentration of trace amounts of mercury(II) in different water samples. Conditions of the analysis such as preconcentration time, effect of pH, sample volumes, shaking time, elution conditions and effects of interfering ions for the recovery of analyte were investigated. The adsorption capacity of nanometer $SiO_2$-PAN was found to be 260 ${\mu}molg^{-1}$ at optimum pH and the detection limit (3$\sigma$) was 0.48 ${\mu}gL^{-1}$. The extractant showed rapid kinetic sorption. The adsorption equilibrium of mercury(II) on nanometer $SiO_2$-PAN was achieved just in 5 mins. Adsorbed mercury(II) was easily eluted with 5 mL of 6 M hydrochloric acid. The maximum preconcentration factor was 50. The method was applied for the determination of trace amounts of mercury(II) in various water samples and industrial effluents.

• Journal of the Korean Data and Information Science Society
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• v.18 no.2
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• pp.457-469
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• 2007

Process Capability Indexes(PCI) are used as the measure for evaluation of process capability analysis and is the statistical method for efficient process control. The fourth generation $PCI(C_{psk})$ is constructed from $C_{pmk}$ by introducing the factor $\mid\mu-T\mid$ in the numerator as an extra penalty for the departure of the process mean from the preassigned target value T And Process Incapability Indexes(PII) are presented by inversing PCI and include the information of PCI. This paper introduces the PII $C_{ss}^*$ provide manager with various information of process and include Gage R&R. PII $C_{ss}^*$ is presented by inversing PCI $C_{psk}$ and include the information of PCI $C_{psk}$.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.10a
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• pp.115-120
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• 1998

This paper is especially concerned with the weldment between support beam and square bar that plays important roles in control box of Expansion Joint as a bridge structure. Fatigue strength of the weldment is dependent on notch radius from welding defects and material properties. From which, tensile strength($\sigma$ult) and fatigue notch factor(Kf) become important factors to predict fatigue life. The fatigue notch sensitivity(η) for metals can be divided into two types : high and low notch sensitivity. In this work, the Expansion Joint weldment was found to have low notch sensitivity. Fatigue test of real structure was performed up to 106cycles to be compared with predicted endurance limit.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.603-606
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• 2000

This dissertation is concerned with ultra-precision profile measurement of aspheric surfaces using contact probing technique. A contact probe has been designed as a sensing device to obtain measuring resolutions in nanometer regime utilizing a leaf spring mechanism and a capacitive-type sensor. The contact probe is attached on the z-axis during measurement while aspheric objects are supported on an precision xy-stage whose lateral motions are monitored by a set of two orthogonal plane mirror type laser interferometers. Experimental results show that the contact probing technique developed in this investigation is capable of providing a repeatability of 50 nanometers with a $\pm$3$\sigma$ uncertainty of 300 nanometers. Thermal disturbance is found the most significant factor that should be precisely controlled for accurate measurement.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.7
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• pp.1155-1162
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• 2001

Sihs minimum strain energy density criterion(SED) often used in the mixed mode problem has the ambiguity of the choice of minimum values. In this paper, as the method to solve the problem of SED, maximum minimum strain energy density criterion is proposed that the crack propagates in the direction of having the maximum among the minimum values of modified strain energy density factor(MS), i.e., sign($\sigma$(sub)$\theta$).Smin.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.1 s.24
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• pp.99-108
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• 2006

In this paper, we analyzed the characteristics of emitter geolocation coverage area within which the emitter lies with a specified probability based on the LOBs(Line of Bearing) of sensors. Stansfield and MSD algorithms were applied to calculate BPE(Best Point Estimate), EEP(Elliptical Error Probable) and CEP(Circular Error Probable), They used the weighting factors composed of ${\sigma}_{Phi}$ (bearing error), QF(quality factor), $P_{e}$ (probability being inside) to optimize the performance. The characteristics of EEP was investigated in the change of them and those of CEP was analyzed based on the deployment of sensors.

• Proceedings of the Korean Society for Quality Management Conference
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• 2004.04a
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• pp.13-18
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• 2004

국내의 제조업과 서비스업은 글로벌 환경, 지식정보화시대, 개방화 등 극심한 경영환경 변화에 노출되어 있다. 적자생존의 법칙이 적용되는 경영현장에서 기업이 지속적으로 성장하기 위해서는 차별적인 경쟁전략이 요구된다고 하겠다. 제품이나 서비스에서 마찬가지로 오차 또는 불량은 고객의 불만과 불평으로 이어져 다시 신뢰를 회복하기 어려울 뿐만 아니라 매출신장이나 서비스 재 구매에도 악영향을 미치게 된다. 따라서 제조업을 막론하고 서비스업에서는 완벽한 품질을 추구해야 한다. 완벽한 품질을 지향하는 것이 '6 시그마'라고 할 수 있다. 1999년 이래로 국내 제조업에서 6시그마 도입이 본격화되면서 서비스업종에서도 6시그마 도입이 점차 증가하고 있고 6시그마 도입에 관심을 갖는 업체들이 늘어나고 있는 추세이다. 본 연구에서는 국내 서비스 기업의 6시그마경영활동과 성과사례를 연구하고 6시그마 도입을 통해서 프로세스측면에서 얻은 경영성과를 확인하고 주요 성공요인들(CSF: Critical Success Factor)을 탐색하기로 한다.

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.04a
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• pp.444-449
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• 2006

6시그마 프로세스는 정의(Define), 측정(Measure), 분석(Analyze), 개선(Improve), 관리(Control)라는 다섯 스텝을 통하여 문제를 해결하고 성과를 달성한다. 이 다섯 단계 중에서 정의 단계는 프로젝트를 선정하고, 고객을 정의하고 프로젝트의 핵심 요인을 파악하며, 팀을 구성하고, 일정을 수립하는 일련의 과정으로서, 6시그마 활동전체의 방향을 제시하는 동시에, 이 활동이 그 조직에 얼마나 효과성이 결정되는 단계로서 6시그마 전 활동을 통하여 가장 중요한 단계라 할 수 있다. 6시그마 활동 중 정의 단계의 4 Step인 Project의 선정, Project의 정의, CTQ의 도출 및 선정, Project의 실행 계획은 프로젝트의 성공과 실패를 좌우하는 중요한 요인이다. 본 연구는 F사에서 수행했던 프로젝트를 대상으로 정의 단계의 각 Step마다 적정한 Activity에 따라 수행되었는가를 분석하여 F사의 6시그마 활동의 문제점을 조사하여 향후 6시그마 활동의 방향을 제시하려한다.

• Bulletin of the Korean Chemical Society
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• v.18 no.2
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• pp.208-212
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• 1997

Theoretical AM1 MO studies are reported on the gas-phase deprotonations of N-methyl 4-((Y-phenylsulfonyl)pyridinium cations (Ⅳ) and N-(Y-benzyl) 4-((phenylsulfonyl)methyl pyridinium cations (Ⅴ) using NH3 as a base. Bronsted α values for deprotonation of Ⅳ and Ⅴ are 0.18 and 0.17, respectively. Bronsted β value of 0.53 is found for the deprotonation of Ⅳ and Ⅴ by substituted aniline bases. The negative transition state (TS) imbalances, Ⅰ(=α-β) < 0, are rationalized by the negative distance factor, Δd (=dp-dTS) < 0, where dp and dTS are the distance between anionic charge center and substituents in the product and in the TS, respectively. The inability of d-pπ-conjugation in Ⅳ, where instead n-σ* type sigma delocalization occurs, causes very little lag in the structural reorganization in the TS.

• Structural Engineering and Mechanics
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• v.88 no.3
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• pp.201-208
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• 2023

In this work, the effect of the correction fibers direction on the efficiency of repairing damaged composite plates was highlighted. The composite plates studied in this work consist of eight layers of graphite/epoxy, while the patch used in this repair consists of four layers of the same type. The results obtained in this work, whether with regard to the experimental or analytical side, showed that the fibers orientation affects the repair efficiency, so the closer the angle of fibers inclination is to the tensile strength direction, the performance of the composite material is ideal. Hence, we conclude that the composite materials with longitudinal fibers (Parallel to tensile strength) is the most powerful and efficient material in performance.